A Global View of the Off-Shell Higgs Portal

TL;DR

This paper evaluates the potential of future colliders to detect off-shell Higgs portal interactions with pseudo Nambu-Goldstone boson dark matter, expanding understanding of collider sensitivity to these models.

Contribution

It provides the first comprehensive analysis of collider reach for the derivative Higgs portal involving pNGB dark matter across various future collider options.

Findings

Future colliders can significantly probe the parameter space of pNGB dark matter.

Off-shell Higgs production via vector boson fusion is a promising detection channel.

Extended results improve constraints on the marginal Higgs portal with undetected scalars.

Abstract

We study for the first time the collider reach on the derivative Higgs portal, the leading effective interaction that couples a pseudo Nambu-Goldstone boson (pNGB) scalar Dark Matter to the Standard Model. We focus on Dark Matter pair production through an off-shell Higgs boson, which is analyzed in the vector boson fusion channel. A variety of future high-energy lepton colliders as well as hadron colliders are considered, including CLIC, a muon collider, the High-Luminosity and High-Energy versions of the LHC, and FCC-hh. Implications on the parameter space of pNGB Dark Matter are discussed. In addition, we give improved and extended results for the collider reach on the marginal Higgs portal, under the assumption that the new scalars escape the detector, as motivated by a variety of beyond the Standard Model scenarios.